Draw a curtain with SMART GLASS

Smart glass, also referred to as privacy glass, is an electric switchable glass with adjustable opacity. It uses electro chromatic technology to interchange between transparent and an opaque state by applying a desired voltage. Privacy Smart glass can change from clear to a frosted appearance at a push of a button!

Two of the smart glass technologies are-

PDLC SMART GLASS TECHNOLOGY

It is a laminated glass product consisting of a Polymer Dispersed Liquid Crystal (PDLC) film sandwiched between two layers of glasses and two layers of conductive interlayer films. The PDLC film is responsible for changing the visual appearance of the glass from opaque to clear on a button press (or dim anywhere in between). When the power is ON and current passes through the glass it aligns LC molecules in the polymers parallel to the incident light thus allowing all the light to pass through. When OFF polymers are arranged randomly that disperse the light and hence making it opaque.

ELECTROCHROMIC GLASS TECHNOLOGY

Electrochromic glass is one that has a coating of metal oxide on to it. The glass consists of five layers-two electrodes and a separator in the middle and two transparent metal contact layers on the either sides of the electrodes. The working involves positively charged lithium ions. When no voltage is applied lithium ions are quietly sticking to inner electrode which is made up of lithium cobalt oxide and makes the glass completely transparent. When a voltage is applied the ions move to the outer electrode made up of polycrystalline tungsten oxide and reflect light thus making the glass opaque. To make it again transparent voltage needs to be applied in reverse direction. The point to note here is that, voltage is required only to change the state of the glass (transparent or opaque), it is not required to maintain the particular state

Advantages & Disadvantages of Smart Glass

ADVANTAGES

Smart glass could benefit environment. In their darkened state, they reflect back virtually all (about 98 percent of) the light falling on them. They keep the inside of the house cool in summers. As they are controlled electrically, they can be automated depending upon the ambient light present in the room or depending upon day and night time. Thus there is no need to draw a curtain manually anymore. According to scientists of US Department of Energy's National Renewable Energy Laboratory (NREL) smart glass could save up to 8 percent of a building's total energy consumption.

DRAWBACKS

The biggest drawback is that smart glass is definitely going to be quite expensive as compare to ordinary glass. They may not have a longer life. Over the period of 5-8 years of deployment the performance starts degrading. Turing of glass from opaque to transparent and vice-a-versa may not be instantaneous, it may take several minutes.

Applications

There can be a huge range of applications, in homes it can replace the ordinary glass so that there is no requirement of curtains any more. In offices it may be used to create partitions which are today done by plywood or by ordinary glass with film on it that does not offer complete privacy if required. In hospitals where hygiene is a major concern, this smart glass eliminates the need for curtains and blinds. In top end cars it can be used to separate driver area from the rear passenger area.

By-Minaxi Dassi, Assistant Professor, ECE, Chitkara University Himachal Pradesh

References
http://www.explainthatstuff.com/electrochromic-windows.html
http://www.smartglass.com/